With the rapid development of network construction and customer application requirements of mobile communication, requirements for the coverage and quality of indoor signals are increasingly growing stronger. The active indoor Distributed Antenna System (DAS) has gradually become a preferable scheme for achieving high quality indoor in-depth coverage. Customers' demands on system reliability, especially concerns about the reliability of active components, are rising as the DAS being used more and more widely. An accessing scheme of 1+1 backup is adopted in some large, importance projects to improve product reliability. However, the 1+1 backup requires more hardware resources while increasing the system redundancy, resulting in an increase of product cost.